Let your imagination run wild and you may eat fewer M&Ms

New research suggests that we can habituate to food items—and decrease our …

Imagine eating an M&M, taking one out of a bowl in front of you, popping it in your mouth, chewing it, enjoying the delicious chocolate flavor, and swallowing it. Now, imagine eating another. And another. Now, here’s the question: after imagining eating 30 of these scrumptious treats, given the chance to actually dive into a bowl of M&Ms, how many would you eat? According to a study in Science last week, you’d eat far fewer chocolates after this mental exercise than you would if you hadn't used your imagination.

The participants were divided into three groups and asked to imagine performing 33 actions. The first group—the control group—had to imagine putting 33 quarters into a laundry machine (an action that is mechanically similar to the process of eating a candy). A second group had to imagine putting 30 quarters into a laundry machine, then eating 3 M&Ms; the final group had to imagine putting three quarters into a laundry machine and eating 30 M&Ms.

After they finished with these tasks, the participants got to eat as many M&Ms as they wanted from a bowl before their next task, a "taste test" that was completely irrelevant to the study. The researchers then calculated how much candy they ate from the bowl.

It turns out that the more M&Ms a participant imagined eating, the fewer they actually ate when the candies were in front of them. People that imagined eating 30 candies ate half as many M&Ms as those who imagined eating just three did. There was no difference between those who imagined eating just three M&Ms and those who only imagined putting coins in a machine.

The study was performed again with cheese cubes instead of chocolate, and the result was the same. Interestingly, further experiments showed that these results were stimulus-specific; that is, imagining eating many M&Ms decreased the number of M&Ms people ate, but not the number of cheese cubes they ate.

So, why does this effect happen? It turns out that the processes of mental imagery (imagining) and perception (actually eating) are very similar, engaging many of the same neural pathways and emotions. Imagining eating a certain food causes your body to habituate to it just as if you were eating it does, and the food becomes less desirable.

Common sense, as well as some previous studies, might have suggested the opposite effect: that thinking about something desirable makes you want it more. Picturing freshly-baked brownies may cause salivation for someone with a sweet tooth, and a smoker thinking about a cigarette may have a sudden craving. The authors suggest that the effect may depend on the kind of mental imagery used. Vividly imagining a brownie or cigarette once may sensitize you to it and increase its desirability, but repeatedly going through the mental motions of actually consuming it seems to make it less attractive.

While the basic finding of this study—that we don’t need to actually experience something to become habituated to it—is interesting enough, your mind is probably already swimming with its applications. This research certainly suggests new possibilities for weight loss, cutting back on alcohol, and quitting smoking. Less obvious applications are also possible, such as decreasing the debilitating effects of some phobias.

Fledgling entrepreneurs take note: there’s nowhere near enough evidence yet to tout the effectiveness of the "mental M&M Diet."

Kate Shaw Yoshida / Kate is a science writer for Ars Technica. She recently earned a dual Ph.D. in Zoology and Ecology, Evolutionary Biology and Behavior from Michigan State University, studying the social behavior of wild spotted hyenas.